Passenger cars have nowadays a number of safety restraint systems, such as seat belts pretensions or airbags, as e.g. front and side airbags, which serve to cushion or limit the impact of a passenger with for example interior parts of passenger cars in case of an accident. Deceleration sensors in the passenger vehicle detect high deceleration values as they occur in case of an accident and send a trigger signal via wire or cable to the safety restraints system. An explosive device, known as squib, inflates the airbag or tightens the belt. The wires or cables of the deceleration sensor are connected to an electronic controlled unit and then to a squib, by means of a so called squib connector.
To this day, the squib is usually provided with a socket or receptacle which contains two contact pins. The squib connector includes a plug part or a plug connector corresponding to the socket, which plug part has two receptacles for the reception of the contact pins of the squib socket. To improve the connection between the squib and the plug connector, retainer inserts were developed, which are configured to fit into the receptacle of standardized squibs and which facilitate and secure the connection between the squib and the plug connector. Alternatively to the use of retainers, connector position assurance members, better known as CPA members, were developed, that are mated with the plug connector after the plug connector is coupled to a corresponding counter connector. Such a CPA member is designed, so that a mating to the plug connector is only possible, if the plug connector is correctly coupled to the corresponding counter connector, i.e. the CPA member cannot be mated to the plug connector, if the plug connector is in an uncoupled or incorrectly coupled condition.
The principle structure of an (airbag) squib is for example described in International Patent Publication No. WO 2004/020933. The squib described in this document includes an outer can enclosing a suitable pyrotechnic charge and an ignitor which is provided with two contact pins being electrically connected to an ignitor wire which can activate the charge of the squib. The ignitor further encloses a retainer for securing the squib to the housing of e.g. an airbag inflator, which retainer further includes a plastic insert, which is injection molded around the pins of the squib and which serves to provide for mechanical fastening with the corresponding (squib) plug connector. The retainer is further provided with a so called shorting clip, which is usually an electro conductive metallic spring part, which in the non-coupled condition electrically connects the two pins of the squib with each other, i.e. shorting the same.
The shorting of the contact pins serves to prevent an unintended explosion of the pyrotechnic charge due to electrical potential differences occurring between the two contact pins, for example during transport or handling. The shorting circuit established by the shorting clip is separated and opens upon correct coupling of the corresponding plug connector into or with the retainer, respectively the corresponding counter connector. Alternatively, the shorting clip can be opened by a CPA member. Usually a contact pin member of a shorting clip is displaced by a plug part of the plug connector so that the two contact pins are no longer electrically connected. These shorting clips of the prior art are not only intended to prevent an unintentional ignition of the charge of the squib, but they also serve as a control or monitoring means of the correct coupling of the (squib) plug connector with its counterpart, i.e. the squib receptacle respectively the retainer or insert mounted therein. Upon correct coupling of the plug connector with its counterpart, the short circuit between the contact pins of the squib is automatically opened as described above, and this can be detected by means of suitable electrical/electronic monitoring means, as it is well known to the skilled person.
In the latest developments, modern squibs are so reliable that a shorting clip is no longer absolutely necessary. Thanks to these improvements, an unintended ignition of the charge due to an electrical potential difference between the contact pins can be ruled out. Thus, for this new type of squib, the shorting clips could be disposed of, thereby reducing the manufacturing costs for the squib connectors considerably. However, the shorting clip is not only a safety feature for an unintended ignition of explosive charge of the airbag or belt pretension system but it is also commonly used to monitor the correct coupling of the plug connector with its counterpart.
International Patent Publication No. WO 2010/143078 discloses a squib connector that allows the electrical monitoring of the correct coupling of the plug connector. Therefore, the terminals of the connector are in electrical contact with each other in the uncoupled or incorrectly coupled condition of the plug connector. This electrical contact between the terminals is configured for being separated upon correct coupling to a corresponding counter connector either automatically, i.e. by a retainer or by an actuating action, such as a mating a CPA member. Thus, disconnecting of the terminals can be monitored by a suitable monitoring means. The electrical contact between the terminals is established by contact means, which are provided with one bendable contact tongue. This bendable tongue is bent out of contact upon correct coupling of the plug connector by e.g. separator.
The separator is an electrical insulator and preferably formed of plastic. The contact surfaces of the shorting clip provided in the plug connector are typically in contact with the separator. Due to the contact, of plastic and metallic surface of the shorting clip, the contact surface of the shorting clip can be contaminated with wear debris of the separator. In particular due to relatively high operation temperatures, typically up to 130° C., the contact surfaces of the shorting clip can be unintentionally coated with residual layers of plastic. This effect is known as fogging. In case of disassembling of the electrical plug connector and a new coupling to a corresponding counter connector, the monitoring function can be distorted due to the residual layers disposed on the contact surfaces of the shorting clip. Further residual layers may derive from the oxidation of the surfaces during the lifespan of the shorting clip. Thus, to avoid the building of residual layers, the contact surfaces are typically coated with e.g. a gold coating. This gold coating obviously increases production costs.
A connector for a safety restraint system which allows the electrical or electronic monitoring of the correct coupling of a (squib) plug connector with its corresponding counterpart, for example a squib receptacle or a retainer insert for a squib receptacle, which is cheaper to produce than the known connectors remains desired.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.